I bet it's the fan spigot blocked, mine does this once a year, esp when damp outside.
But I'm afraid you need an RGI for this and any other poss combustion fault.
Happy New Year.
Look up Hinton Heating - good bloke in your area
But I'm afraid you need an RGI for this and any other poss combustion fault.
Happy New Year.
Look up Hinton Heating - good bloke in your area